mirror of
https://github.com/cc65/cc65.git
synced 2024-07-05 21:29:03 +00:00
113 lines
1.9 KiB
ArmAsm
113 lines
1.9 KiB
ArmAsm
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; Startup code for cc65 (Apple2 version)
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;
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; This must be the *first* file on the linker command line
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;
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.export _exit
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.import __hinit
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.import zerobss, push0, doatexit
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.import _main
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.include "apple2.inc"
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; ------------------------------------------------------------------------
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; Define and export the ZP variables for the C64 runtime
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.exportzp sp, sreg, regsave
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.exportzp ptr1, ptr2, ptr3, ptr4
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.exportzp tmp1, tmp2, tmp3, tmp4
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.exportzp regbank, zpspace
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; These zero page entries overlap with the sweet-16 registers.
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; must be changed if sweet-16 is to be supported
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sp = $00 ; stack pointer
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sreg = $02 ; secondary register/high 16 bit for longs
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regsave = $04 ; slot to save/restore (E)AX into
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ptr1 = $08 ;
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ptr2 = $0A
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ptr3 = $0C
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ptr4 = $0E
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tmp1 = $10
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tmp2 = $11
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tmp3 = $12
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tmp4 = $13
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regbank = $14 ; 6 byte register bank
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zpspace = $1A ; Zero page space allocated
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; ------------------------------------------------------------------------
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; Actual code
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ldy #zpspace-1
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L1: lda sp,y
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sta zpsave,y ; Save the zero page locations we need
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dey
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bpl L1
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; Clear the BSS data
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jsr zerobss
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; Save system stuff and setup the stack
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tsx
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stx spsave ; Save the system stack ptr
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lda #<TOPMEM
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sta sp
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lda #>TOPMEM
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sta sp+1 ; Set argument stack ptr
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; Initialize the heap
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jsr __hinit
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; Initialize conio stuff
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lda #$ff
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sta TEXTTYP
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; Set up to use Apple ROM $C000-$CFFF
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;; sta USEROM
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; Pass an empty command line
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jsr push0 ; argc
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jsr push0 ; argv
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ldy #4 ; Argument size
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jsr _main ; call the users code
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; fall thru to exit...
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_exit:
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lda #$ff
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sta TEXTTYP
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jsr doatexit ; call exit functions
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ldx spsave
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txs ; Restore stack pointer
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; Copy back the zero page stuff
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ldy #zpspace-1
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L2: lda zpsave,y
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sta sp,y
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dey
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bpl L2
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; Reset changed vectors, back to basic
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jmp RESTOR
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.data
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zpsave: .res zpspace
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.bss
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spsave: .res 1
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